Photolithography equipment is used in the processing of semiconductor wafers. In this equipment, a wafer to be processed is placed on a stage or other support platform which is movable to align the wafer with respect to the photolithography equipment. Two sources of forces can disturb the alignment. The movement of the payload generates reaction forces which cause the stage to vibrate and move the lens assembly, potentially disturbing the alignment. Also, the vibrations can take substantial time to dissipate, and during this time, the wafer cannot be exposed. Additionally, seismic level base disturbances can affect the alignment. Typically, prior art stepper systems are isolated from seismic disturbances, whereas the stage motions are optimized to reduce reaction forces.